Amines Caffeine. Nitrogen Chemistry Nitrogen will readily form 3 covalent bonds (each atom already...
-
Upload
nelson-mckenzie -
Category
Documents
-
view
223 -
download
0
Transcript of Amines Caffeine. Nitrogen Chemistry Nitrogen will readily form 3 covalent bonds (each atom already...
Nitrogen Chemistry
Nitrogen will readily form 3 covalent bonds (each atom already has 5 v.e-)– Carbon forms 4 covalent bonds– Oxygen forms 2 covalent bonds
Structure & Classification of Amines
Amines are derivatives of ammonia (NH3)
Functional group = NHx
Aromatic amines = aniline -->
Amine Nomenclature IUPAC (longest chain = alkane)
– Primary Alkanamine
– # is used to ID location of fcn’l group on alkane chain
– Can have diamines, etc.
– Secondary N-alkylalkanamine
– Tertiary N-alkyl-N-alkylalkanamine
– Multifunctional groups Amine = substituent (amino),
– Carboxylic acid– Aldehyde– Ketone– Alcohol– Amine
Common– Primary
Alkylamine
– Secondary Alkylalkylamine
– Tertiary Alkylalkylalkylamine
Isomers– Skeletal (C atoms)– Positional (NHx group)
Physical Properties of Amines
State: low MW = gases @ RT– Smell like ammonia
– high MW = liquids @ RT– Bad odors
BP: alkanes<amines<alcohols– Hydrogen bonding
Water solubility– Low MW = v. soluble– High MW = soluble
Amines are weak Bases NH3 + HOH <==> NH4
+ + OH-
ammonium ion
CH3-NH2 + HOH <==> CH3-NH3+ + OH-
methylamine methylammonium ion methanamine
Amine Salts– Acid + amine --> Amine salt + water (protonation)
HCl + CH3-NH2 --> CH3-NH3+Cl-
methylammonium chloride– Amine salt + base --> amine + salt + water (deprotonation)
CH3-NH3+Cl- + NaOH --> CH3-NH2 + NaCl + HOH
Preparation of Amines Alkylation in the presence of a base
– Ammonia + alkyl halide --> 1˚ amine NH3 + CH3Cl --> CH3NH3
+Cl- + NaOH --> CH3NH2 + NaCl + HOH The primary amine will continue to react unless it is removed as it is produced.
– 1˚ amine + alkyl halide --> 2˚ amine– 2˚ amine + alkyl halide --> 3˚ amine– 3˚ amine + alkyl halide --> quaternary ammonium salt
– Quaternary ammonium salts may be biochemically important
Ex.: choline (growth reg.) & acetylcholine (nerve impulse transmission)
Heterocyclic AminesNitrogen atoms are part of a ring system
Hemoglobin -pyrrole derivative
Nicotine Caffeine - pyridine derivative -purine derivative
Biochemically Important Amines Neurotransmitters
– Acetylcholine, norepinephrine
– Dopamine, serotonin
Epinephrine– Adrenaline– Amphetamines - structurally related to adrenalin
Histamine– Responsible for effects of hay fever & pollen allergies– These effects are counteracted by antihistamines
Alkaloids - plant based amines
Nicotine, caffeine, cocaine
Chocolate
Quinine, atropine
Opium– Codeine, Morphine (heroin)
The alkaloid atropine is obtained from the belladonna plant.
Poppy
Theobromine - Greek (“theo” - god; “brosis” - food)
What do you need to know?– Structural characteristics (know the functional group)
Carboxylic Acids Esters Phosphate Esters Amides Amines Isomers; Functional group isomers
– Nomenclature (the rules for naming the molecules) Common & IUPAC
– Amides: (alkylalkylamide) N-alkylalkanamide – Amines: (alkylalkylamine) N-alkylalkanamine
– Physical properties (basic/simple) pH; BP; Solubility; Flammability
– Acids ~ hydrogen bonding!– Esters ~ no hydrogen bonding (a lot like ethers)– Amides: lower pH; most are solids @ RT– Amines: higher pH; most are liquids @ RT
– Occurrence and uses (common) Acids - metabolic intermediates & products; antimicrobials Esters - flavors/fragrances; pheromones; medications
– Phosphate esters Amides - Urea; barbiturates; polyamides & polyurethanes Amines - Biochemical; Alkaloids
– Preparation (what basic reactions produce the molecules) Acids - Oxidation of aldehydes; of alkyl benzene Esters - Esterification (C. acid + alcohol); condensation polymerization Amides - (amidification) Amine + C. Acid --> amide Amines - Rxn w/ alkyl halide (in base)
– Characteristic reactions of the molecules Acids - Neutralization; Esterification; acid salts (rxn w/ SB or SA) Esters - Ester Hydrolysis (in acid); Saponification (in base) Amides - Hydrolysis (acidic & basic); polymerization Amines - Protonation<==> Deprotonation